1. Field of the Invention
The present invention is directed to detergent compositions containing substantially pure EG III cellulase from Trichoderma spp. as well as to methods for employing such compositions. In particular, the detergent compositions of the present invention comprise a cleaning effective amount of one or more surfactants and substantially pure EG III cellulase.
2. State of the Art
Cellulases are known in the art as enzymes that hydrolyze cellulose (.beta.-1,4-glucan linkages) thereby resulting in the formation of glucose, cellobiose, cellooligosaccharides, and the like. While cellulases are produced (expressed) in fungi, bacteria and the like, cellulase produced by certain fungi and, in particular by the fungal class Trichoderma spp. (especially Trichoderma longibrachiatum), have been given the most attention because a complete cellulase system capable of degrading crystalline forms of cellulose is readily produced in large quantities via fermentation procedures.
In regard to the above, Schulein, "Methods in Enzymology", 160, 25, pages 234 et seq. (1988), disclose that complete fungal cellulase systems comprise several different enzyme classifications including those identified as exo-cellobiohydrolases (EC 3.2.1.91) ("CBH"), endoglucanases (EC 3.2.1.4) ("EG"), and .beta.-glucosidases (EC 3.2.1.21) ("BG"). The fungal cellulase classifications of CBH, EG and BG can be further expanded to include multiple components within each classification. For example, multiple CBHs and EGs have been isolated from a variety of fungal sources.
The complete cellulase system comprising CBH, EG and BG components is required to efficiently convert crystalline cellulose to glucose. Isolated components are far less effective, if at all, in hydrolyzing crystalline cellulose. Moreover, a synergistic relationship is observed between the cellulase components particularly if they are of different classification.
On the other hand, cellulases and components thereof, used either singularly or in combination, are also known in the art to be useful in detergent compositions. For example, endoglucanase components of fungal cellulases have been used for the purposes of enhancing the cleaning ability of detergent compositions, for use as a softening agent, and for use in improving the feel of cotton fabrics, and the like. However, there is a problem with using the EG I and EG II components derived from Trichoderma spp. and especially Trichoderma longibrachiatum in detergent compositions. Specifically, such components have their maximal activity at acidic pHs whereas most laundry detergent compositions are formulated for use at neutral or alkaline (pH&gt;7 to about 10) conditions. While it is disclosed in U.S. Ser. No. 07/668,640 that the use of one or more acidic endoglucanase components of Trichoderma longibrachiatum in detergent compositions will provide improvements in softening, color retention/restoration and feel to cotton-containing fabrics even when treated under alkaline conditions, the present invention is directed to the discovery that the EG III component of Trichoderma spp. provides for superior and unexpected advantages in detergent compositions as compared to the EG I and EG II components of Trichoderma longibrachiatum.
Specifically, this component has been found to possess significant enzymatic activity under alkaline conditions.